diff --git a/Lib/distutils/sysconfig.py b/Lib/distutils/sysconfig.py
index 33cc5a3..d206e0c 100644
--- a/Lib/distutils/sysconfig.py
+++ b/Lib/distutils/sysconfig.py
@@ -389,7 +389,7 @@
         cur_target = os.getenv('MACOSX_DEPLOYMENT_TARGET', '')
         if cur_target == '':
             cur_target = cfg_target
-            os.putenv('MACOSX_DEPLOYMENT_TARGET', cfg_target)
+            os.environ['MACOSX_DEPLOYMENT_TARGET'] = cfg_target
         elif map(int, cfg_target.split('.')) > map(int, cur_target.split('.')):
             my_msg = ('$MACOSX_DEPLOYMENT_TARGET mismatch: now "%s" but "%s" during configure'
                 % (cur_target, cfg_target))
diff --git a/Lib/distutils/tests/test_build_ext.py b/Lib/distutils/tests/test_build_ext.py
index 86568eb..46dcb5e 100644
--- a/Lib/distutils/tests/test_build_ext.py
+++ b/Lib/distutils/tests/test_build_ext.py
@@ -3,12 +3,13 @@
 import tempfile
 import shutil
 from StringIO import StringIO
+import textwrap
 
 from distutils.core import Extension, Distribution
 from distutils.command.build_ext import build_ext
 from distutils import sysconfig
 from distutils.tests import support
-from distutils.errors import DistutilsSetupError
+from distutils.errors import DistutilsSetupError, CompileError
 
 import unittest
 from test import test_support
@@ -430,6 +431,59 @@
         wanted = os.path.join(cmd.build_lib, 'UpdateManager', 'fdsend' + ext)
         self.assertEqual(ext_path, wanted)
 
+    @unittest.skipUnless(sys.platform == 'darwin', 'test only relevant for MacOSX')
+    def test_deployment_target(self):
+        self._try_compile_deployment_target()
+
+        orig_environ = os.environ
+        os.environ = orig_environ.copy()
+        self.addCleanup(setattr, os, 'environ', orig_environ)
+
+        os.environ['MACOSX_DEPLOYMENT_TARGET']='10.1'
+        self._try_compile_deployment_target()
+
+
+    def _try_compile_deployment_target(self):
+        deptarget_c = os.path.join(self.tmp_dir, 'deptargetmodule.c')
+
+        with open(deptarget_c, 'w') as fp:
+            fp.write(textwrap.dedent('''\
+                #include <AvailabilityMacros.h>
+
+                int dummy;
+
+                #if TARGET != MAC_OS_X_VERSION_MIN_REQUIRED
+                #error "Unexpected target"
+               #endif
+
+            '''))
+
+        target = sysconfig.get_config_var('MACOSX_DEPLOYMENT_TARGET')
+        target = tuple(map(int, target.split('.')))
+        target = '%02d%01d0' % target
+
+        deptarget_ext = Extension(
+            'deptarget',
+            [deptarget_c],
+            extra_compile_args=['-DTARGET=%s'%(target,)],
+        )
+        dist = Distribution({
+            'name': 'deptarget',
+            'ext_modules': [deptarget_ext]
+        })
+        dist.package_dir = self.tmp_dir
+        cmd = build_ext(dist)
+        cmd.build_lib = self.tmp_dir
+        cmd.build_temp = self.tmp_dir
+
+        try:
+            old_stdout = sys.stdout
+            cmd.ensure_finalized()
+            cmd.run()
+
+        except CompileError:
+            self.fail("Wrong deployment target during compilation")
+
 def test_suite():
     return unittest.makeSuite(BuildExtTestCase)
 
diff --git a/Lib/distutils/util.py b/Lib/distutils/util.py
index f06e4fd..6c49f0b 100644
--- a/Lib/distutils/util.py
+++ b/Lib/distutils/util.py
@@ -97,9 +97,7 @@
         from distutils.sysconfig import get_config_vars
         cfgvars = get_config_vars()
 
-        macver = os.environ.get('MACOSX_DEPLOYMENT_TARGET')
-        if not macver:
-            macver = cfgvars.get('MACOSX_DEPLOYMENT_TARGET')
+        macver = cfgvars.get('MACOSX_DEPLOYMENT_TARGET')
 
         if 1:
             # Always calculate the release of the running machine,
diff --git a/Lib/sysconfig.py b/Lib/sysconfig.py
index 3146f30..9e8acc5 100644
--- a/Lib/sysconfig.py
+++ b/Lib/sysconfig.py
@@ -297,21 +297,6 @@
             msg = msg + " (%s)" % e.strerror
         raise IOError(msg)
 
-    # On MacOSX we need to check the setting of the environment variable
-    # MACOSX_DEPLOYMENT_TARGET: configure bases some choices on it so
-    # it needs to be compatible.
-    # If it isn't set we set it to the configure-time value
-    if sys.platform == 'darwin' and 'MACOSX_DEPLOYMENT_TARGET' in vars:
-        cfg_target = vars['MACOSX_DEPLOYMENT_TARGET']
-        cur_target = os.getenv('MACOSX_DEPLOYMENT_TARGET', '')
-        if cur_target == '':
-            cur_target = cfg_target
-            os.putenv('MACOSX_DEPLOYMENT_TARGET', cfg_target)
-        elif map(int, cfg_target.split('.')) > map(int, cur_target.split('.')):
-            msg = ('$MACOSX_DEPLOYMENT_TARGET mismatch: now "%s" but "%s" '
-                   'during configure' % (cur_target, cfg_target))
-            raise IOError(msg)
-
     # On AIX, there are wrong paths to the linker scripts in the Makefile
     # -- these paths are relative to the Python source, but when installed
     # the scripts are in another directory.
@@ -616,9 +601,7 @@
         # machine is going to compile and link as if it were
         # MACOSX_DEPLOYMENT_TARGET.
         cfgvars = get_config_vars()
-        macver = os.environ.get('MACOSX_DEPLOYMENT_TARGET')
-        if not macver:
-            macver = cfgvars.get('MACOSX_DEPLOYMENT_TARGET')
+        macver = cfgvars.get('MACOSX_DEPLOYMENT_TARGET')
 
         if 1:
             # Always calculate the release of the running machine,
diff --git a/Lib/test/test_sysconfig.py b/Lib/test/test_sysconfig.py
index 142eb2f..95fbe0e 100644
--- a/Lib/test/test_sysconfig.py
+++ b/Lib/test/test_sysconfig.py
@@ -141,7 +141,7 @@
                    ('Darwin Kernel Version 8.11.1: '
                     'Wed Oct 10 18:23:28 PDT 2007; '
                     'root:xnu-792.25.20~1/RELEASE_I386'), 'PowerPC'))
-        os.environ['MACOSX_DEPLOYMENT_TARGET'] = '10.3'
+        get_config_vars()['MACOSX_DEPLOYMENT_TARGET'] = '10.3'
 
         get_config_vars()['CFLAGS'] = ('-fno-strict-aliasing -DNDEBUG -g '
                                        '-fwrapv -O3 -Wall -Wstrict-prototypes')
@@ -161,7 +161,6 @@
                     'Wed Oct 10 18:23:28 PDT 2007; '
                     'root:xnu-792.25.20~1/RELEASE_I386'), 'i386'))
         get_config_vars()['MACOSX_DEPLOYMENT_TARGET'] = '10.3'
-        os.environ['MACOSX_DEPLOYMENT_TARGET'] = '10.3'
 
         get_config_vars()['CFLAGS'] = ('-fno-strict-aliasing -DNDEBUG -g '
                                        '-fwrapv -O3 -Wall -Wstrict-prototypes')
@@ -176,7 +175,7 @@
             sys.maxint = maxint
 
         # macbook with fat binaries (fat, universal or fat64)
-        os.environ['MACOSX_DEPLOYMENT_TARGET'] = '10.4'
+        get_config_vars()['MACOSX_DEPLOYMENT_TARGET'] = '10.4'
         get_config_vars()['CFLAGS'] = ('-arch ppc -arch i386 -isysroot '
                                        '/Developer/SDKs/MacOSX10.4u.sdk  '
                                        '-fno-strict-aliasing -fno-common '
@@ -265,6 +264,51 @@
             user_path = get_path(name, 'posix_user')
             self.assertEqual(user_path, global_path.replace(base, user))
 
+    @unittest.skipUnless(sys.platform == "darwin", "test only relevant on MacOSX")
+    def test_platform_in_subprocess(self):
+        my_platform = sysconfig.get_platform()
+
+        # Test without MACOSX_DEPLOYMENT_TARGET in the environment
+
+        env = os.environ.copy()
+        if 'MACOSX_DEPLOYMENT_TARGET' in env:
+            del env['MACOSX_DEPLOYMENT_TARGET']
+
+        with open('/dev/null', 'w') as devnull_fp:
+            p = subprocess.Popen([
+                    sys.executable, '-c',
+                   'import sysconfig; print(sysconfig.get_platform())',
+                ],
+                stdout=subprocess.PIPE,
+                stderr=devnull_fp,
+                env=env)
+        test_platform = p.communicate()[0].strip()
+        test_platform = test_platform.decode('utf-8')
+        status = p.wait()
+
+        self.assertEqual(status, 0)
+        self.assertEqual(my_platform, test_platform)
+
+
+        # Test with MACOSX_DEPLOYMENT_TARGET in the environment, and
+        # using a value that is unlikely to be the default one.
+        env = os.environ.copy()
+        env['MACOSX_DEPLOYMENT_TARGET'] = '10.1'
+
+        p = subprocess.Popen([
+                sys.executable, '-c',
+                'import sysconfig; print(sysconfig.get_platform())',
+            ],
+            stdout=subprocess.PIPE,
+            stderr=open('/dev/null'),
+            env=env)
+        test_platform = p.communicate()[0].strip()
+        test_platform = test_platform.decode('utf-8')
+        status = p.wait()
+
+        self.assertEqual(status, 0)
+        self.assertEqual(my_platform, test_platform)
+
 def test_main():
     run_unittest(TestSysConfig)